Wireless Measurement System using Zigbee Transmission implemented on TES

Transcription

1 International Journal of Advances in Electrical and Electronics Engineering 151 Available online at & ISSN: Wireless Measurement System using Zigbee Transmission implemented on TES C. Padmini 1,G. Bhaskar Phani Ram 2, Venkat B Prashanth 2 1 Asst. Professor(Sr. Grade ), 2 Asst.Professor, Department of Electronics & Communication Engineering, Vardhaman College of Engineering, Hyderabad, A.P-India bhaskarram1984@gmail.com ABSTRACT- In this paper we are going to present a new application that use Zigbee radio modules for implementation of distributed system intended for continuous monitoring and controlling of radiation level in surveillance area like frontiers, customs supervising offices, Nuclear plants, civil areas. The remote modules periodically read signals from sensors and send result to the controller board that display the received data on LCD Panel. In sensor networks a set of nodes randomly deployed communicate through wireless links and provide the information as on when required. Since these nodes run with little power mostly running with batteries the hardware and software must be designed appropriately. In this paper, TEA is implemented using Zigbee wireless link. The use of Zigbee Module and Microcontroller ensures a robust and secure communication between system modules with Low power consumption. Key Words: Sensors, LCD Panel, TES Algorithm, Zigbee Module. I. INTRODUCTION Radiation level measurement and monitoring of parameters like temperature, gas etc., in nuclear power plants is a very important problem that imposes the implementation of distributed surveillance systems. Usually these type of systems use networks of sensors for detection. Besides the quality and sensibility of the sensors, the connections to the monitoring system of large number of sensor raise some difficulties when wires are used. The advantage of using these radio technologies are the flexibility in topology implementation and reorganization of the measurement systems as well as the possibility of realization of portable devices connected to a measuring and monitoring system with in an area. Security and accuracy are major concerns. So to overcome these issues the data should be encrypted to provide security for secret data. In this paper we implement Tiny Encryption Algorithm (TEA) at the either nodes. II.WIRELESS SENSOR NETWORKS BASED ON ZIGBEE TECHNOLOGY The Zigbee is a new technology that permits the implementation of Wireless Personal Area Networks (WPAN). It is very suitable for wireless sensor networks due to low power consumption. This was one of the reasons for the implementation of the system.the advantages of Zigbee with other technologies are : Low Cost Low Power Consumption Flexible Network Architecture Fig.1 Summarizes topologies types for Wireless sensor N/Ws.In the structure of Zigbee networks the devices can be of tree types: Zigbee Coordinator, Zigbee Router and Zigbee end device. Zigbee Coordinator (ZC): It has the function to initiate the network structure by configuring the channels and establishing an ID for the network. Zigbee Router (ZR): It acts as an Intermediate Device, Its main function is to participate in multihop/mesh routing of network messages.

2 Wireless Measurement System using Zigbee Transmission implemented on TES 152 Zigbee end device: It does not participate in routing. It contains only the functionality to communicate with parent node. Figure 1: Topologies types for Wireless sensor N/Ws III.TINY ENCRYPTION SPECIFICATION (TES) ALGORITHM TEA operates on 64-bit blocks and uses a 128-bit key. It has a Feistel structure with a suggested 64 rounds, typically implemented in pairs termed cycles. It has an extremely simple key schedule, mixing all of the key material in exactly the same way for each cycle. The Tiny Encryption Algorithm uses operations from mixed (orthogonal) algebraic groups. A dual shift causes all bits of the data and key to be mixed repeatedly. The key schedule algorithm is simple; the 128-bit key K is split into four 32-bit blocks K = (K [0], K [1], K [2], K [3]). Figure 2 shows the structure of the TEA encryption routine. The inputs to the encryption algorithm are a plaintext block and a key K.The plaintext is P = (Left[0], Right [0]) and the cipher text is C = (Left [64], Right [64]). The plaintext block is split into two halves, Left [0] and Right [0]. Each half is used to encrypt the other half over 64 rounds of processing and then combine to produce the cipher text block. It shows the structure of the TEA encryption routine. The inputs to the encryption algorithm are a plaintext block and a key K.The plaintext is P = (Left [0],Right [0]) and the cipher text is C = (Left [64], Right [64]). The 128-bit key K is split into four 32-bit blocks K = (K [0], K [1], K [2], K [3]). The keys K[0] and K[1] are used in the odd rounds and the keys K[2] and K[3] are used in even rounds. The plaintext block is split into two halves, Left [0] and Right [0]. Each half is used to encrypt the other half over 64 rounds of processing (32 cycles) and then combine to produce the cipher text block.

3 IJAEEE,Volume2, Number 1 C. Padmini et at. Figure 2: The abstract structure of TEA encryption routine. i th Cycle: Each round i has inputs Left[i-1] and Right[i-1], derived from the previous round, as well as a sub key K[i] derived from the 128 bit overall K as shown in the figure 3. The sub keys K[i] are different from K and from each other. The constant delta = ( 5-1)*2 31 = 9E3779B9 h, is derived from the golden number ratio to ensure that the sub keys are distinct and its precise value has no cryptographic significance. The round function, F, consists of the key addition, bitwise XOR and left and right shift operation. We can describe the output (Left [i +1], Right [i +1]) of the ith cycle of TEA with the input (Left[i], Right[i]) as follows Left [i+1] = Left[i] F (Right[i], K [0, 1], delta), Right [i +1] = Right[i] F (Right [i +1], K [2, 3], delta), The round function, F, is defined by,

4 Wireless Measurement System using Zigbee Transmission implemented on TES 154 F (M, K [j,k], delta[i] ) = ((M << 4) K[j]) (M delta[i] ) ((M >> 5) K[k]). The round function has the same general structure for each round but is parameterized by the round sub key K[i]. Figure 3.3 shows an abstraction of i-th cycle of TEA. Significance of Delta : Figure 3: An abstraction of i th cycle of TEA. The constant delta = ( 5-1)*2 31 = 9E3779B9 h, is derived from the golden number ratio to ensure that the sub keys are distinct and its precise value has no cryptographic significance. Different multiples of a magic constant are used to prevent simple attacks based on the symmetry of the rounds. The magic constant, or 9E3779B9 16 is chosen to be 2 32 /ϕ, where ϕ is the golden ratio. Two quantities are in the golden ratio if the ratio of the sum of the quantities to the larger quantity is equal to the ratio of the larger quantity to the smaller one. Expressed algebraically as: Where a > b. The golden ratio is denoted by the Greek lowercase letter phi (ϕ ) This equation has one positive solution in the set of algebraic irrational numbers: Decryption Routine: Decryption is essentially the same as the encryption process; in the decode routine the cipher text is used as input to the algorithm, but the sub keys K[i] are used in the reverse order. It makes use of subtraction, XOR and shifting operations. Figure 4 shows the TEA decryption routine.

5 IJAEEE,Volume2, Number 1 C. Padmini et at. Figure 4: The abstract structure of TEA decryption routine. IV.IMPLEMENTATION OF TEA TEA is used to encrypt the 64 bit sensor data at the transmitter and transmit the cipher text to the receiver using a single ended wireless communication link. TEA is implemented in the ARM7-TDMI based LPC2148 microcontroller. The main peripherals of the LPC2148 microcontroller which has been used for this purpose are UART0, UART1 and ADC0.LPC2148 is interfaced with the temperature sensor at the transmitter end and Zigbee modules both at the transmitter and the receiver ends.

6 Wireless Measurement System using Zigbee Transmission implemented on TES 156 Figure 5: Secure Wireless Communication Link The single ended wireless link consists of a transmitter and a receiver. At the transmitter, the temperature sensor, LM35 is interfaced with LPC2148 microcontroller which is connected to the PC. The input sensor data is encrypted using the encryption algorithm and the cipher text is sent to the receiver through the zigbee module. the peripherals used here are ADC0 at the transmitter end and a pair of UART0 and UART1 at both the transmitter and the receiver ends. Two zigbee modules are interfaced with the two microcontrollers at transmitter and the receiver to set a wireless communication link. The LPC2148 microcontroller at the receiver is also connected to another PC. The receiver receives the encrypted data and the decryption algorithm is implemented to receiver the actual transmitted data. The terminal displays the data at the transmitter and the receiver. V.FUTURE SCOPE The tiny encryption algorithm is one of the most secure cipher algorithms ever devised and certainly the simplest. It is very secure and the code is lightweight and portable enough to be used just about anywhere. The minor weaknesses identified by David Wagner at Berkeley are unlikely to have any impact in the real world, and the user can always implement the new variant TEA which addresses them. To cater for these weaknesses the algorithm readily adjusted while trying to retain the original objectives of little set up time, simplicity and using a large number of rounds to prevent attacks and avoid complicated analysis. But if the requirement is a low-overhead end to-end cipher (for real-time data, for example), then TEA fits the bill. It can be shortened or made faster but the version given by the inventers is the simplest to implement or remember. A simple improvement is to copy k [0-3] into a, b, c, d before the iteration so that the indexing is taken out of the loop. In one implementation it can reduce the time by about 1/6 th.it can be implemented as a couple of macros which would remove the calling overheads. VI.CONCLUSION The main aim of this paper is to provide security and reliability to the wireless communication link using encryption. As compared to the other encryption algorithms, the Tiny Encryption Algorithm (TEA) is more efficient in terms of memory footprint and implementation. The microcontroller which has

7 IJAEEE,Volume2, Number 1 C. Padmini et at. been used is LPC2148 with ARM7-TDMI S architecture, is capable of transmitting and receiving data. The use of Zigbee module makes the communication link more secure and faster in terms of data transfer and wake up delay. Hence, the equipment has a wide range of applications given that there are numerous advantages over other wireless communication links..references [1] L.F. Akyildiz, W. Su, Y. Sankarasubramaniam, E. Cayirci, Wireless Sensor Networks: A Survey, Comput. Netw, vol. 38, pp , 2002 [2] J. Hong, Q. Zhu, J. Xiao, Design and Realization of Wireless Sensor Network Gateway Based on ZigBee and GPRS. Second International Conference on Information and Computing Science, Manchester, UK, [3] K. Osberg, N. Schemm, S. Balkir, s.a., A hand-held neutron detection sensor system, IEEE International Symposium on Circuits and Systems, May [4] J. Hong, Q. Zhu, J. Xiao, Design and Realization of Wireless Sensor Network Gateway Based on ZigBee and GPRS. Second International Conference on Information and Computing Science, Manchester, UK, 2009.